The benefits of using hydraulic fracturing (HF) to stimulate
gas and oil flow from both new and existing wells are obvious.
However, the downside is that this technique consumes huge
quantities (along the lines of millions of gallons per well) of
often regionally scarce water. Opponents to HF also claim this
process can contaminate drinking water supplies. The US Environmental Protection Agency
recently initiated a new, science-based study to determine if
the (HF) practice does indeed pose a risk to human health or
the environment.

Meeting the challenge.

To help address some of the water-related issues, several
leading water-technologies companies have introduced mobile
water treatment solutions. These mobile units are designed to
treat and to recycle both HF flowback and brine water produced
during drilling, HF and other industrial operations. Such
efforts reduce the strain on freshwater supplies. Onsite water
treatment also lowers the need to transport HF flowback and
produced water offsite for safe disposal. Water technology companies are also
building permanent treatment facilities designed to lower the
percentage of total dissolved solids from the HF flowback
produced water before processing at municipal wastewater
treatment facilities that often are not
equipped to handle this effluent type.

R&D efforts.

In addition, several universities, including Texas A&M,
Carnegie Mellon University and West Virginia University have
initiated research projects (often involving
substantial funding from the US Department of Energy) intended
to develop new, more effective technologies for treating
effluents from oil and gas drilling and HF operations.

HF consume huge quantities of water.

With HF, water under high pressure forms fractures in the
rock, which are propped open by sand or other materials thus
providing pathways for gas (and oil) to move to the well.
Petroleum engineers refer to this fracturing process as
stimulation. A variety of different chemicals,
typically representing less than 0.5% of the total volume, are
also used to facilitate this process. The tremendous volumes of
water required (typically two to five million gallons per
well), of which 25% to 100% may be returned to the surface as
flowback water, must be recovered and disposed of responsibly
(or recycled for further industrial usage) before gas
production can commence.

For western US states, in particular, freshwater supplies
are already extremely scarce; thus, HF can further strain
existing water resources. Water used for drilling and fracking
active wells in the Barnett Shale area can equal the typical
water usage for 185,000 households (or more).

According to a US Geological Survey (USGS) fact sheet, Texas
state and county agencies now closely monitor volumes of water
used during drilling, and a consortium of Barnett Shale
drilling companies have developed best-management practices for
water conservation. The goal is to keep the pace of drilling
and production activities within the bounds of sustainable
water usage. Producers in Marcellus Shale gas production areas
have had similar discussions.

Reduce, reuse and recycle.

Water treatment solutions enable water reuse to reduce
freshwater and transportation requirements. Produced water from
HF operations is typically disposed of in three ways:
1. Transported offsite for disposal in permitted
underground wells
2. Transported offsite for treatment before disposal to
surface waters
3. Treated onsite for reuse in HF or drilling
operations

The unique nature of the flowback water produced from HF
operations located in different geographic regions (and
different chemicals used) requires different water-treatment
solutions. For example, water treatment operations in the
Marcellus Shale region in the eastern US must be able to deal
with the extremely high-brine content of the HF flowback
water.

Several companies, including both Siemens Water Technologies
and GE Power & Water, have introduced mobile treatment
units that can treat produced water onsite for reuse via a
variety of different technologies. The onsite approach both
reduces the strain on local water resources and minimizes the
cost, wear on roads and greenhouse-gas emissions associated with hauling
large quantities of flowback and produced water to distant
disposal wells or offsite treatment facilities in tank trucks. The
Siemens solution utilizes flotation/filtration technology, while the GE solution
utilizes evaporation methodology. As with most technology approaches, each has its
pros and cons.

Clearly, the limited availability of water appropriate for
HF operations constrains the oil and gas industrys
ability to produce shale gas and other unconventional energy
sources. Furthermore, the present high cost of treating and/or
transporting and disposing of both produced water and HF
flowback water represents a considerable cost. The current
concerted effort by leading water indus-try suppliers,
government and academia to develop, commercialize and deploy
new mobile and fixed technologies for cost-effectively treating
produced water and HF flowback water will provide significant
benefit to the oil and gas industry and the general public.

ARC Advisory Group is preparing a series of reports on
industrial water management for its Advisory Service clients.
These reports will include approaches and success stories.
HP

The author

Paul Miller is a senior
editor/analyst at ARC Advisory Group and has 25 years
of experience in industrial automation industry. He
has published numerous articles in industry trade
publications. Mr. Miller follows both the terminal
automation and water/wastewater sectors for ARC. For
more information, readers can contact the author at
pmiller@arcweb.com.

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